These are some characters that I think would be good in a MK game

Jason Voorhees

The predator

Terminator

Xenomorph

Micheal myers

Rick "splatterhouse"

Isaac Clarke "dead space"

Pinhead

Pennywise

Ash "evil dead"

Sweet tooth "twisted metal"

Duke Nukem

Cyber reptile

Cyber smoke

Riddick

Spawn

Hellboy

Blade